Low boiler feed water responsive safety valves for shutting down boiler feed pump turbine



y 1958 E. A. CUNNINGHAM. JR.. ETAL 2,842,151

, LOW BOILER FEED WATER RESPONSIVE SAFETY VALVES FOR SHUTTING DOWNBOILER FEED PUMP TURBINE Filed Aug. 9, 1955 2 Sheets-Sheet 1 HEADERSUPPLY RETURN 70 suppl Y SUPPLY FEED WA 75!? DRAIN TO SUPPLY INVENTORS.EDWIN A. CUN/W/VGHAM, c/R. GEORGE R. ANDERSON y 8, 1958 E. A.CUNNINGHAM. JR.. ET AL 2,842,151

LOW BOILER FEED WATER RESPONSIVE SAFETY VALVES FOR SHUTTING DOWN BOILERFEED PUMP TURBINE Filed Aug. 9, 1955 2 Sheets-Sheet 2 INVENTORS. EDWINA. CUNNINGHAM, JR.

GEORGE R. ANDERSON Unified ates Patent LOW BOILER FEED WATER RESPONSIVESAFETY VALVES FOR SHUTTlNG DOWN BOILER FEED PUMP TURBINE Edwin A.Cunningham, Jr., Whitehall, and George R. Anderson, Mount LebanonTownship, Allegheny County, Pa., assignors to Hagan Chemicals &Controls, Inc., a corporation of Pennsylvania Application August 9,1955, SerialNo. 527,266

Claims. (Cl. 137-95) This invention relates to safety devicesforturbinedriven boiler feed pumps and more particularly to devices forshutting down the turbine if and when the pressure in the boiler feedline drops below a predetermined value.

An object of this invention is to provide a device having meansresponsive to pressure in the boiler feed line which shuts oif the oilsupply to the governor valve of the turbine when the pressure dropsbelow a predetermined point.

Another object of the invention is to provide a device having a governortrip valve which is normally biased to closed position but which ismanually set in open position and held in that position by a feed waterpressure controlled latch which is disengaged from the valve when thepressure drops to a predetermined low point thereby shutting oil the oilpressure to the turbine governor valve and stopping the turbine.

Other objects of the invention will in part be apparent and will in partbe obvious to those of ordinary skill in the art to which the inventionpertains from the following description taken in conjunction with theaccompanying drawings.

In the drawings:

Figure 1 is a more or less diagrammatic view illustrating a steamturbine driven boiler feed water pump provided with a safetydevice forshutting down the turbine if and when the boiler feed water pressuredrops below a predetermined low value, the safety device being arrangedand constructed in accordance with an embodiment of the invention; and

Figure 2 is a view in section of the safety device illustrated in Fig.1.

In Fig. l of the drawings is shown schematically a boiler 1 thatsupplies steam through a line 2 in which is a governor valve 3, to aturbine 4 that drives a boiler feed pump 5. The feed water is taken bypump 5 from a supply source 6 and delivered through line 7 to theboiler. A check valve 8 is in the feed line 7 to prevent reverse flowtherein. The boiler 1 supplies steam for purposes other than therequirements of turbine 4. Turbine 4 as shown drives the water feed pump5 only.

The governor valve 3 is actuated by an operator 9 which is supplied withoil at such pressures that the valve 3 is positioned in accordance withthe demand for steam by the turbine. The oil for the operator 9 issupplied by a pump 11 to a safety device 12 and thence to the operator9. The pump 11 takes the oil from a supply source not shown and deliversthe oil at pressures that vary with changes in speed of the turbine.

Operator 9 comprises a cylinder 13 having a piston 14 therein that isbiased in a direction to close valve 3 by means of a spring 15. Thepiston 14 is urged downwardly to open the valve 3 by oil admitted underpressure through a pipe 16 which is delivered through the safety tripdevice 12.

The piston 14 is provided with a piston 17 that extends downwardlythrough the bottom of the cylinder 13 and is connected to a crosshead 18of a yoke which is conice nected to the valve 3. The yoke includes rods19 and 20 connected at their lower ends to the opposite ends of thecrosshead 18 and at their upper ends to a crosshead 21. The crosshead 21is connected to the valve stem 22 of valve 3.

The top of piston 14 is provided with a stem or rod 23 that extendsupwardly through the head 24 of cylindcr 13 and terminates within ahousing 25. Within the housing 25 is a bellows 26 the upper end of whichis connected to the rod 23 and the lower end of which is joined bywelding or brazing to the head 24 to provide a fluid-tight joint andseal about the aperture through which the rod 23 extends. A spring 27tends to elongate the bellows 26. Oil under pressure is supplied to thehousing 25 which tends to push downwardly on the pis- 1 ton 14.

The rod 17 is sealed at the location where it passes through the base ofcylinder 13 by means of a bellows 29 the upper end of which is securedin fluid-tight relation to the base of the cylinder, the opposite end ofbellows 29 being secured in fluid-tight relationship with the crosshead18.

The oil supplied to the governor operating valve mechanism 9 is derivedfrom the pump 11 as stated. The oil is delivered to an inlet pipe 30 ofdevice 12 and discharged therefrom into a pipe 31. In pipe 31 is anorifice 32 and in pipe 16 is an orifice 33. The portion of the pipebeyond orifice 32 supplies oil through a pipe 34 to the housing 25. Theextension of the pipe 31 beyond the orifice 32 supplies pilot oil toother units (not shown) of the power plant in which the turbine 4, pump5 and boiler 1 are incorporated.

The safety trip device 12 is illustrated more in detail in Fig. 2. Asthere shown, the device comprises a valve body 36 having a ported sleeve37 in the bore 38 thereof. The sleeve 37 has a bore 39 in which a valveplug 40 is disposed. The valve plug is provided with lands 41 and 42separated by a connecting spindle 43. The sleeve 37 is provided with aninlet port 45 that communicates with t a port in the body to which thepipe 30 is connected and it is provided with an outlet port 46 thatcommunicates with a port in the body to which the outlet pipe 31 isconnected. The sleeve 37 is provided with annular grooves 47 and 48 thatcommunicate with the inlet and outlet ports of the valve as shown. Thesleeve is also provided with an annular groove 49 in the region of land41. The sleeve 39 is ported at the annular groove 49 and connected to adrain pipe 50 that leads back to the supply of oil to which the intakeof pump 11 is connected.

Sleeve 37 is also provided with an annular groove 51 located to the leftof the inlet port 45 as shown in Fig. 2 and that groove connects thesleeve bore 39 with a drain passage 52 leading to the drain pipe 50.Thus any oil that leaks towards the left-hand end of the valve plug isdrained to the drain port pipe 50.

The left-hand end of valve plug 40 is connected by a pin 54 to a slide55 disposed in the bore 38. The end of the slide 55 to which the valveplug 40 is connected is enlarged as shown and is hollow to accommodate atrigger 56 that is pivotally supported by a pin 57. The trigger 56 isurged counterclockwise against a stop pin 58 by means of a slide plug 59and a spring 60 housed in the bore of the slide 55. The spring is heldin compression against the slide plug 59 by means of a screw plug 61within the slide 55 and which is secured in position by means of a pin62.

The slide 55 is urged to the right as seen in Fig. 2 by means of acompression spring 63 disposed about the slide 55 and within the housingbore 38. The spring is held in compression by means of a cap 64 securedto the left-hand end of the valve body as shown.

When the valve plug is in the position shown. in Fig. 2 the inlet portis closed and the governor valve operator 9 is connected through theoutlet port 46 to the drain pipe 50. When the valve plug is pulled tothe left by means of the hand wheel or knob 66 to a position Where theland 42 is to the left of the inlet port 45, the oil supply pipe 30 isconnected to the outlet pipe 31 and the operator 9.

In order to hold the valve plug 40 in its open position a pressureactuated latch or trigger keeper 67 is provided. The keeper 67 isoperatively disposed in a sleeve 68 the lower end of which is secured ina base plate 69 and the upper end of which is housed within a bellows70. The bellows 70 in turn is housed in a housing 71. the upper end ofwhich is closed as shown and the lower open end of which is connected inpressure-tight relationship with a flange 72 secured to a mounting plate73. The mounting plate 73 is carried by spacers '74 through which bolts75 extend and are threaded into the base plate 69 and the valve body.

The upper end of the bellows 70 is secured by welding or otherwise to abearing member 77 into which the upper end of the latch 67 extends asshown. The latch 67 is urged upwardly by a compression spring 80disposed about the sleeve 68. As shown,-the upper end of the spring 80bears against the bearing member 77 and the lower end is supported on anadjustable nut 81 by means of which the initial compressive tension inthe spring 80 and the pressure at which the trigger is released maybeadjusted. For the purpose of adjustment, the lower end of the nut 81 isprovided with wrench sockets 83.

The housing 71 is provided with an inlet fitting 84 whereby the interiorof the housing 71 may be connected to the feed water supply pipe 7 andthereby cause the bellows 70 to be compressed and the trigger keeper 67urged downwardly.

When the pressure in the feed water line 7 is at or above apredetermined minimum value and the slide 55 is pulled to the left asshown in Fig. 2, the pressure acting on the bellows 70 will move thekeeper 67 downwardly until its notched end 86 engages the end 87 of thetrigger 56. When so engaged the valve plug 40 is held in open position.So long as the valve is in open position oil is supplied to the governorvalve operating mechanism 9. As soon as the pressure in the feed line 7drops below a predetermined value the bellows 70 elongates andapproaches the position shown in Fig. 2, and the moment the notched end86 of the latch 67 is disengaged from the end 87 of the trigger 56, thevalve plug 40 is actuated to its closed position, whereby the oil supplyto the piston 14 is shut off and the valve 3 is closed by the closingaction of the spring 15. Valve plug 40 cannot be reset in open positionuntil the condition which caused the low boiler feed pressure, usuallyflashing at the intake to the boiler feed pump, has been corrected.

Having thus described the invention, it will be apparent to those ofordinary skill in the art to which the invention pertains that variousmodifications and changes may 4 be made in the illustratedembodirnentthereof. Therefore, what is claimed as new and desired to "be secured byLetters Patent is:

1. A safety valve for shutting oil? the oil supply to the governor valveof a steam turbine driving a boiler feed pump in response to lowpressure in the boiler feed line, which safety valve comprises a valvehaving a body provided with supply, outlet and drain ports, the outletport being for supplying the governor valve, a valve plug in the body,the plug when in its off position shutting off the supply port andconnecting the outlet port to drain, and when in its on positionconnecting the supply to the outlet port, a slide in said body connectedto said valve plug, means yieldingly urging the slide in a direction toshift the valve plug to off position, a trigger pivotally supported bythe slide, a trigger keeper adapted to engage the trigger when the slideis in a position to hold the valve plug in on position, means urging thekeeper out of engagement with the trigger and means including a pressuredefiectable member adapted to be acted upon by the pressure of theboiler feed Water to maintain engagement of the keeper with the triggerand thereby hold the valve in its on position so long as the pressure isabove a predetermined value and to release the latch from the I triggerwhen the feed pressure drops below said value.

2. A valve as in claim 1 in which the trigger is of substantiallyL-shaped, the end of one leg of which is engaged by the keeper, aslidable plug engages the upper leg of the trigger and a compressionspring in the slide urges the plug against the trigger to normallymaintain the trigger in a position to be engaged by the keeper.

3. A valve as in claim 1 in which the pressure deflectable means is abellows, a housing encloses the bellows and receives the boiler feedwater pressure, and in which means are provided for adjusting the keeperurging means whereby the pressure at which the trigger is released canbe predetermined.

4. A valve as in claim 2 in which the keeper operates at right angles tothe axis of rotation of the trigger and the keeper is provided at itstrigger engaging end with notched shoulder for receiving the cooperatingend of the trigger.

5. A valve as in claim 1 in which the means embodying the pressuredeflectable member comprises a housing having a bellows therein, thetrigger keeper extends in the bellows and is secured at one end thereto,the means urging the keeper to trigger released position is acompression spring within the bellows, one end of the spring engagingone end of the bellows and the other end engaging an adjustable support,whereby the force of the spring may be adjusted to predetermine thepressure at which the keeper is released from the trigger.

References Cited in the file of this patent UNITED STATES PATENTS1,419,331 Veenschoten June 13, 1922 1,643,483 Barrett Sept. 27, 19272,676,574 Wenzel Apr. 27, 1954

